Data acquisition from an electrical power system helps and operator understand how energy is being consumed by the power system. However, measured data is scalar without the context of when the measured data was actually captured. Ideally, time would be uniform and fixed across the power system, but time is not homogeneous in practical applications. Time is a relative concept that is subject to different variables such as the location, accuracy, and precision of a clock. Because of these and other intrinsic complications, a simple timestamp is often insufficient to precisely describe the temporal moment when a given data point was captured. This problem becomes readily apparent in power monitoring systems, especially as more monitoring devices are incorporated into the power system.
Aligning the magnitude and occurrence of electrical data (voltage, current, energy, demand, events, time, etc.) received from monitoring devices is a valuable tool for end-users. It is difficult to align two or more monitoring device's data together although these devices may record data simultaneously. The end-user must align events on the power system manually by analyzing the data received from the monitoring devices and interpreting that data. In such a case, it can be difficult to even align events or data that occur on different days, much less the same day.
One technique for temporally aligning data across a power monitoring system employs a global positioning satellite (GPS) time system. GPS time systems provide monitoring devices with a synchronized clock signal that insures all power system device clocks are set to the same value. Such GPS systems are expensive because end-users must purchase and install additional hardware and data lines to link each device together and/or to the GPS time signal. Power system devices must be capable of recognizing, receiving, and acting upon the GPS time system's protocol accordingly. Power system devices that do not employ an on-board clock do not have a reference that can be “adjusted” by the GPS time system, and GPS time systems are useless in this case. In certain configurations, latencies may be introduced into the hardware associated with processing time delays. Also, the loss of the time synchronization signal anywhere between the GPS satellite and the monitoring device can result in the loss of synchronization across the power monitoring system.
What is needed, therefore, is a more robust and less expensive system and method for synchronizing data in a utility system. Aspects of the present invention address these and other needs.